Classifications of Rocks. 



47 



which is here given in a tabular form, that it coincides so well 

 with that which has been already used for the practical pur- 

 poses already mentioned, as to admit of their both standing 

 together. Very few modifications were, in fact, required to 

 permit the same enumeration to serve for both ; and thus two 

 modes of division have been applied to the same list. Thus, 

 one of them represents what may hereafter be rendered a 

 natural classification in reality, as it is, now, but an attempt 

 at one ; while the other is an artificial one, which may safely 

 be adopted, at least as such, subject always to future amend- 

 ment. I have merely numbered the new classes for the pre- 

 sent, from an aversion to introducing new terms. If geologists 

 shall approve of this plan under the present or some modified 

 form, it is possible they may not feel the same dislike to the 

 Greek compounds, of which I have merely suggested the first. 

 I know not very well, if there must be a name, what better 

 expedient could be devised. 



ARTIFICIAL SYSTEM. 



PRIMARY CLASS. 

 STRATIFIED. 



Gneiss. 

 tMicaceous schist. 



Chlorite schist. 



Talcose schist, partial. 



Hornblende schist. 



Actinolite schist, partial. 

 ♦Quartz rock. 

 *Red sandstone, 

 f Argillaceous schist, fine clay slate and graywake. 



Diallage rock. 



Serpentine, ambiguous. 

 ♦Limestone. 



Compact felspar, partial. 



Jasper modified from * 1 „ r . 



Siliceous schist, modified from 1 1 W , here gramte ° r 



Chert, modified from $ when ar- f tra P. T P resent ' 

 gillaceous. J P artiah 



UNSTRATIFIED. 



Granite, from the ordinary appearance to that of 



greenstone and basalt. 

 C. felspar porphyry, where decidedly limited] Often 



to the primary strata [doubt- 



Clinkstone and claystone, in the same cases J ful. 

 Serpentine, when solely connected with primary 



strata, or granite. 



NATURAL 

 SYSTEM. 



CLASS 1. 



Protolith? 

 &c. 



CLASS 2. 



